Title Primjena Kubelka-Munk teorije i Yule-Nielsenovog efekta na tiskovnim podlogama Author Vesna Džimbeg-Malčić Mentor Stanislav Bolanča (mentor)Committee member Zdenka Bolanča (član povjerenstva) Committee member Đurđica Parac-Osterman (član povjerenstva) Committee member Stanislav Bolanča (član povjerenstva)Committee member Diana Milčić (član povjerenstva)Committee member Nikola Mrvac (član povjerenstva) Granter University of Zagreb Defense date and country 2005-7-12, Croatia Scientific / art field, TECHNICAL SCIENCES Universal decimal classificationUDC ) 655 - Graphic industries. Printing. Publishing. Book trade Abstract U ovom radu provedena su spektrofotometrijska mjerenja tiskovnih podloga, te obojenih
otisaka. Otisci su dobiveni klasičnim ofsetom amplitudnom i frekventnom rasterskom
modulacijom za osnovna bojila CMYK.
Optičke veličine koje karakteriziraju tiskovne podloge i otiske kao što su raspršenje i
apsorpcija ispitivani su preko Kubelka-Munk teorije, dok je bočno raspršenje pojava koju
opisuje Yule-Nielsenov parametar n. Kubelka –Munk teorija se koristi dugo i uspješno
upravo zato jer osnovne optičke veličine tiskovnih površina i obojenih otisaka, opacitet,
raspršenje i apsorpciju, opisuje preko reflektancije ili transmitancije koje se eksperimentalno
određuju veoma precizno i jednostavno.
Murray-Daveisova metoda tokove fotona zbraja linearno, prema zakonu sačuvanja energije
fotona, ali daje prevelike iznose reflektancije u odnosu na mjerene. Yule i Nielsen zbrajaju
tokove fotona na faktor 1/n, uvodeći na taj način efekt bočnog raspršenja.
Eksperimentalno dobiveni refleksijski spektari matematički su obrađeni da bi osigurali
neophodne podatke za izračun fizikalnih veličina prema pretpostavkama korištenih teorija.
Matematička obrada eksperimentalnih podataka provedena je programima MathCAD 2002
Professional i Data Analysis and Technical Graphics Origin 6.0.
Bočno raspršenje svjetlosti u papiru je osnovni uzrok optičkog prirasta rasterskog elementa.
Naime, svjetlost koja ulazi u papir između rasterskih elemenata može se bočno raspršiti u
papiru prije nego se vrati na površinu kao reflektirana svjetlost. To povećava vjerojatnost da
će svjetlost naići na rastersku točku i da će biti apsorbirana. Zbog toga je efektivni udarni
presjek apsorpcije rasterske točke veći od fizičke veličine točke.
Važno je, prema svemu izloženom, povezati Yule-Nielsenov parametar n, kao mjeru bočnog
raspršenja, s fundamentalnim fizikalnim i optičkim parametrima sustava, da bi se preko njih
mogla predvidjeti veličina optičkog prirasta rasterskog elementa. Ti fizikalni, odnosno optički
parametri su upravo raspršenje i apsorpcija Kubelka-Munk teorije.
Na temelju eksperimentalnih mjerenja i matematičkih rezultata odredilo se je područje
primjene navedenih teorija s obzirom na realne uvjete grafičke reprodukcije i uspostavila se je
korelacija između relevantnih parametara.
Abstract (english) In this thesis spectrophotometric measurements of the choosen paper substrates and coloured
prints have been performed. The prints were obtained by classical offset, amplitude and
frequency screen modulation, for primary colours CMYK.
The optical values which characterize the printing surfaces and prints such as scattering and
absorption were investigated according to Kubelka-Munk theory, while the lateral scattering
is the appearance which is described by the Yule-Nielsen parameter n. Kubelka-Munk theory
has been used successfully for a long time because the basic optical values of the printing
surfaces and coloured prints, opacity, scattering and absorption are described by reflectance
and transmission which are experimentally determined very precisely and simply.
Conservation of photon energy suggest the Murray-Davies method, photon flux add linearly,
but the reflectance predicted by Murray-Davies equation is generally higher than the
measured reflectance. Yule and Nielsen correct Murray-Davies equation adding photon flux
by power factor of 1/n and in that way describe lateral scattering.
The fundamental cause of optical dot gain is lateral scattering of light within paper. Light that
enters the paper between the halftone dots can scatter laterally within the bulk of the paper
before returning to the surface as reflected light. This lateral scattering in the bulk of the
paper increases the probability the light will encounter a halftone dot and be absorbed. Thus
the effective absorption cross section of the halftone dot is larger than the physical size of the
dot.
The obtained experimental data of the reflection spectra were processed mathematically in
order to obtain the necessary data for calculation of the physical values according to the
suppositions of the used theories.
Mathematical processing of the experimental data was performed by means of the programs
MathCAD 2002 Professional and Data Analysis and Technical Graphics Origin 6.0.
According to all the mentioned, it is important to connect the Yule-Nielsen parameters n, as
the measure of the lateral scattering, with the fundamental physical and optical parameters of
the system in order to foreseen the size of the optical dot gain. These physical, i.e. optical
parameters are scattering and absorption of Kubelka-Munk theory.
On the basis of the experimental measurements and mathematical results the area of the
application of the mentioned theories in regard to the real conditions of the graphic
reproduction has been determined and the correlation among the relevant parameters has been
established.
Keywords
Kubelka-Munk koeficijenti
Yule-Nielsenov parametar n
raspršenje
apsorpcija
tiskovna podloga
Keywords (english)
Kubelka-Munk coefficients
Yule-Nielsenov parameter n
scattering
absorption
paper substrate
Language croatian URN:NBN urn:nbn:hr:216:149581 Study programme Title: Graphic engineering and graphic product design Type of resource Text File origin Born digital Access conditions Open access Terms of use Created on 2024-04-24 22:28:02
